Technical Field
The present disclosure relates generally to the field of combustion burners and methods of use, and more specifically to burners, submerged combustion melters, and methods of their use, particularly for melting glass-forming materials.
Background Art
A submerged combustion melter (SCM) may be employed to melt glass batch and/or waste glass materials to produce molten glass by passing oxygen, oxygen-enriched mixtures, or air along with a liquid, gaseous and/or particulate fuel (some of which may be in the glass-forming materials), directly into a molten pool of glass, usually through burners submerged in a glass melt pool. The introduction of high flow rates of products of combustion of the oxidant and fuel into the molten glass, and the expansion of the gases during submerged combustion (SC), cause rapid melting of the glass batch and much turbulence.
In the context of SCMs, known oxy-fuel burners are predominately water-cooled, nozzle mix designs and avoid premixing for safety reasons due to the increased reactivity of using oxygen as the oxidant versus air. One currently used submerged combustion burner employs a smooth exterior surface, half-toroid metallic burner tip of the same or similar material as the remainder of the burner. When operating and SCM with burners of this nature, the combustion burner tips are exposed to a glass and combustion gas environment high and oscillating temperatures. The burner can be designed so that the oxidant (typically oxygen) or fuel flow cools the inner wall of the burner tip before combustion occurs, but the flow cannot provide cooling to the top crown and outer wall of the burner tip. Although cooling water or other coolant is typically applied to cool the burner tip, the temperatures are extremely high for typical metal alloys when the hot glass (2500+° F. (1,370+° C.)) or combustion products (up to 4000° F. (2,190° C.) contact the burner tip. Also, since the burner tip section temperature is oscillating with the combustion bubble growth, the burner tip experiences frequent rapid temperature change. Therefore, burner life can be very short due to the failure of the materials used to form the burner tip.
Development of submerged combustion burners having longer life and less susceptibility to the SCM environment while melting glass-forming materials would be a significant advance in the submerged combustion art.